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Although real-time monitoring of bladder volume together with intravesical pressure can provide more information for understanding the functional changes of the urinary bladder, it still entails difficulties in the accurate prediction of real-time bladder volume in urodynamic studies with small animal models. We studied a new implantable bladder volume monitoring device with eight rats. During cystometry, microelectrodes prepared by the microelectromechanical systems process were placed symmetrically on both lateral walls of the bladder, and the expanded bladder volume was calculated. Immunohistological study was done after 1 week and after 4 weeks to evaluate the biocompatibility of the microelectrode. From the point that infused saline volume into the bladder was higher than 0.6 mL, estimated bladder volume was statistically correlated with the volume of saline injected (p<0.01). Additionally, the microelectromechanical system microelectrodes used in this study showed reliable biocompatibility. Therefore, the device can be used to evaluate changes in bladder volume in studies with small animals, and it may help to provide more information about functional changes in the bladder in laboratory studies. Furthermore, owing to its biocompatibility, the device could be chronically implanted in conscious ambulating animals, thus allowing a novel longitudinal study to be performed for a specific purpose.

Recently, bearingless rotation motors have become widely popular in office automation (OA) and factory automation (FA) systems due to their simple structure, high speed of operation, and high precision in positioning. In this study, a bearingless rotation motor was designed to have a large torque and levitation force because these are generally considered as indicators of motor performance. The torque and levitation force of the bearingless rotation motor can be calculated by a commercial finite element method (FEM) program, ANSYS. To robustly design the bearingless rotation motor, first, the effective design parameters were selected; we set a table of orthogonal arrays, including the design variables and parameters. The Kriging model was applied to formulate the cost function of the regression model, which can be used to evaluate the motor performance. By minimizing the cost function, it was possible to quickly realize a robust optimum design of a bearingless rotation motor. As a result, the performance of the motor was improved with regard to the torque and levitation force.

Many aging people and patients have difficulties in bladder control. Its symptoms are largely urinary frequency and urinary incontinence, which can cause life-threatening illnesses. A therapeutic research for bladder nerves and surgical treatment has been studied. However, such treatments are likely to cause complications and need more reliability and safety. An urodynamic study, which is designed to monitor the relationship between flow, pressure, and volume by inserting a condom catheter into the urethra, is most commonly used for the measurement of bladder operation. Unfortunately, this method may cause inconvenience and side effects. Thus, a urinary tract-bladder-resembling experimental device was manufactured and used for the study based on experimental data. Similar research to human urinary tract-bladder dynamics is lacking. Therefore, this study intended to design mechanical urinary-bladder simulator, which resembled the urinary tract system including the bladder, ureter, and urethra. The fluid mechanical urinary tract-bladder simulator was manufactured by using a pump, hose, flow-meter, pressure sensor, rubber membrane, syringe and control software. In addition, the unique pressure-volume relationship in the bladder and urination affected by abdominal pressure could be comprehended with the use of the manufactured simulator. In this simulator, bladder pressure change and urination control were reproduced by the pump and valve by letting water flow in, while non-linear increase and reduction of pressure was reproduced by application of abdominal pressure on the elastic rubber membrane and plastic hemispherical capsule-connected syringe. The abdominal pressure added in the system can expect to reproduce other types of urinary symptoms. As a result, the fluid mechanical simulator made it possible to reproduce human urinary tract bladder urodynamics movement. This simulator will be effectively used for reliability and stability of the research for the improvement of bladder management that is currently lacking reliability and stability. It can also be utilized for the future application. The fluid mechanical simulator can be useful method to avoid other difficulties which are unpredictable conditions of the human body or seeking the approval of the IRB(Institutional review board) for bioethics. Additionally, an invasive bladder monitoring system that utilizes the simulator has been developing that will benefit patients.

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